scholarly journals Mathematical Modeling of Diurnal Patterns of Turbulent Heat Fluxes using Modified Aerodynamic Resistance Method

2018 ◽  
Vol 6 (6) ◽  
Author(s):  
R. T. Akinnubi ◽  
O. O. Oketayo ◽  
B. F. Akinwale ◽  
M. O. Ojo ◽  
A. Ikusika
Keyword(s):  
Surface Temperature ◽  
Aerodynamic Resistance ◽  
Surface Heat ◽  
Heat Fluxes ◽  
Mean Bias Error ◽  
Turbulent Heat ◽  
Surface Heat Fluxes ◽  
Diurnal Patterns ◽  
Turbulent Heat Fluxes ◽  
Following Error

The development of improved methods for estimating turbulent heat fluxes is important in effective monitoring of the surface energy balance for climate change prediction. However, different  parameterized models carried out at the local site of Nigerian Micrometeorological site (NIMEX-1) did not consider the surface heat fluxes-aerodynamics resistance relationships, and these validated models cannot be incorporated into the Climate models because some of the input climate variables are not routinely available in some meteorological stations. This study therefore, aims at improving the diurnal patterns of surface heat fluxes estimates using radiometric surface temperature and aerodynamic surface-layer resistances. Hourly data of air temperature (Ta), soil temperature (Tsoil), global radiation (QL), surface temperature (Ts), wind speed (u), QH and QE were obtained from the NIMEX-1 at Ile-Ife (7.55 oN, 4.55 oE). The QH and QE were estimated using Aerodynamic Resistance Approach algorithm which was modified to reduce the large bias errors between the aerodynamic temperature and surface temperature above the ground level. The algorithms were validated and rated using the following error statistics: coefficient of determination (r2), Mean Bias Error (MBE) and Root Mean Square Error (RMSE). The RMSE and MBE for the modeled QE estimated using ARM and MAR reduced from 28.33Wm-2 to 14.33 Wm-2 and 36.93 to 10.74 Wm-2 respectively while for QH ,the RMSE and MBE reduced from 17.29 Wm-2 to 9.49 Wm-2 and 31.39 to 16.93 Wm-2 respectively. The r2 values ranged from 0.68 to 0.73 and 0.95 to 0.98 for QH and QE respectively. The MAR had the highest r2 and least error values.  Hence, the proposed modified Aerodynamic resistance models are estimated the diurnal and seasonal turbulent heat fluxes accurately for tropical regions.

scholarly journals Large-eddy simulations of marine boundary-layer clouds associated with cold air outbreaks during the ACTIVATE campaign– part 1: Case setup and sensitivities to large-scale forcings

2021 ◽  
Author(s):  
Xiang-Yu Li ◽  
Hailong Wang ◽  
Jingyi Chen ◽  
Satoshi Endo ◽  
Geet George ◽  
...  
Keyword(s):  
Large Scale ◽  
Field Measurements ◽  
Reanalysis Data ◽  
Surface Heat ◽  
Heat Fluxes ◽  
Turbulent Heat ◽  
Liquid Water Path ◽  
Surface Heat Fluxes ◽  
Large Eddy ◽  
Turbulent Heat Fluxes

Abstract Large-eddy simulation (LES) is able to capture key boundary-layer (BL) turbulence and cloud processes. Yet, large-scale forcing and surface turbulent fluxes of sensible and latent heat are often poorly prescribed for LES simulations. We derive these quantities from measurements and reanalysis obtained for two cold air outbreak (CAO) events during Phase I of the Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE) in February-March 2020. We study the two contrasting CAO cases by performing LES and test the sensitivity of BL structure and clouds to large-scale forcings and turbulent heat fluxes. Profiles of atmospheric state and large-scale divergence and surface turbulent heat fluxes obtained from the reanalysis data ERA5 agree reasonablywell with those derived fromACTIVATE field measurements for both cases at the sampling time and location. Therefore, we adopt the time evolving heat fluxes, wind and advective tendencies profiles from ERA5 reanalysis data to drive the LES.We find that large-scale thermodynamic advective tendencies and wind relaxations are important for the LES to capture the evolving observed BL meteorological states characterized by the hourly ERA5 reanalysis data and validated by the observations. We show that the divergence (or vertical velocity) is important in regulating the BL growth driven by surface heat fluxes in LES simulations. The evolution of liquid water path is largely affected by the evolution of surface heat fluxes. The liquid water path simulated in LES agrees reasonably well with the ACTIVATE measurements. This study paves the path to investigate aerosol-cloud-meteorology interactions using LES informed and evaluated by ACTIVATE field measurements.

Sea Surface Heat Fluxes and Fortnightly Modulation of the Surface Temperature within the Ballenas Channel, Gulf of California

2013 ◽  
Vol 292 ◽  
pp. 1400-1412 ◽  
Author(s):  
A. Martínez-Díaz-de-León ◽  
Rubén Castro ◽  
E. Santamaría-del-Ángel ◽  
I. Pacheco-Ruiz ◽  
R. Blanco-Betancourt
Keyword(s):  
Surface Temperature ◽  
Gulf Of California ◽  
Surface Heat ◽  
Heat Fluxes ◽  
Sea Surface ◽  
Surface Heat Fluxes

Augmentations to the Noah Model Physics for Application to the Yellow River Source Area. Part II: Turbulent Heat Fluxes and Soil Heat Transport

2015 ◽  
Vol 16 (6) ◽  
pp. 2677-2694 ◽  
Author(s):  
Donghai Zheng ◽  
Rogier van der Velde ◽  
Zhongbo Su ◽  
Xin Wang ◽  
Jun Wen ◽  
...  
Keyword(s):  
Heat Flux ◽  
Organic Matter ◽  
Surface Temperature ◽  
Heat Transport ◽  
Yellow River ◽  
Turbulent Heat Flux ◽  
Heat Fluxes ◽  
The Yellow River ◽  
Turbulent Heat ◽  
Turbulent Heat Fluxes

Abstract This is the second part of a study on the assessment of the Noah land surface model (LSM) in simulating surface water and energy budgets in the high-elevation source region of the Yellow River. Here, there is a focus on turbulent heat fluxes and heat transport through the soil column during the monsoon season, whereas the first part of this study deals with the soil water flow. Four augmentations are studied for mitigating the overestimation of turbulent heat flux and underestimation of soil temperature measurements: 1) the muting effect of vegetation on the thermal heat conductivity is removed from the transport of heat from the first to the second soil layer, 2) the exponential decay factor imposed on is calculated using the ratio of the leaf area index (LAI) over the green vegetation fraction (GVF), 3) Zilitinkevich’s empirical coefficient for turbulent heat transport is computed as a function of the momentum roughness length , and 4) the impact of organic matter is considered in the parameterization of the thermal heat properties. Although usage of organic matter for calculating improves the correspondence between the estimates and laboratory measurements of heat conductivities, it is shown to have a relatively small impact on the Noah LSM performance even for large organic matter contents. In contrast, the removal of the muting effect of vegetation on and the parameterization of greatly enhances the soil temperature profile simulations, whereas turbulent heat flux and surface temperature computations mostly benefit from the modified formulation. Further, the nighttime surface temperature overestimation is resolved from a coupled land–atmosphere perspective.

scholarly journals Estimation of surface heat fluxes using multi-angular observations of radiative surface temperature

2020 ◽  
Vol 239 ◽  
pp. 111674 ◽  
Author(s):  
Lisheng Song ◽  
Zunjian Bian ◽  
William P. Kustas ◽  
Shaomin Liu ◽  
Qing Xiao ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Surface Heat ◽  
Heat Fluxes ◽  
Surface Heat Fluxes ◽  
Radiative Surface Temperature ◽  
Angular Observations
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